For a variety of reasons, most of which relate to environmental and alternative energy pursuits, certain primary fuel engines, such as diesel engines, can be made to accommodate alternate fuels, such as straight vegetable oil (SVO), “biodiesel,” and other fuel oils (hereinafter “alternate fuels”). However, practical applications have demonstrated that some alternate fuels cannot be used in their pure or neat form under all engine and environmental conditions and must be blended with the primary fuel.
Recently, one method for the creation of motor fuels with alternate fuel content has been accomplished by blending primary and alternate fuels at or before the end user distribution point at low ratio to ameliorate alternate fuel negative attributes such as higher viscosity and the tendency to congeal at low temperatures, a common example being twenty percent alternate fuel to eighty percent primary fuel by volume. While this has benefit in allowing most engines designed to run on diesel to utilize a degree of alternate fuel, this methodology constrains the end user to a fixed ratio designed for worst-case utilization conditions, and in doing so effectively forfeits optimal utilization of the alternate fuel as actual end use conditions would otherwise permit.
Another limitation occurs if the alternate fuel is of renewable or other classifiable form (hereinafter “renewable”) whereby governmental entities may choose to institute tax credits or assign renewable identification numbering (hereinafter “RIN”) tracking and trading to both encourage renewable energy utilization and penalize those that abstain. In such a case, constraining the use of renewable fuels to a fixed blending ratio at time of motor fuel creation as constrained by ameliorating negative renewable fuel attributes creates penalties at multiple levels. For the environment, the reduction of potential renewable energy usage by fixed blending prevents maximal reduction of greenhouse gases by requiring an unnecessarily high component of fossil fuel. For the end user, the reduction of potential renewable energy usage by fixed blending reduces the tax credit available per gallon of motor fuel consumed. For the renewable fuel producer, the reduction of potential renewable energy usage by fixed blending caps potential end use within motor fuel and artificially constrains demand. Furthermore, RIN separation that would otherwise been possible at higher blend ratios will be forfeited, forcing RIN generation elsewhere, or raising the cost of RINs due to diminished supply.
Recently, another method for the creation of motor fuels with alternate fuel content has been accomplished by the selection of primary fuel and alternate fuel stored in separate fuel storage vessels, whereby selection is a manual or automated process. While this has benefit in allowing a higher utilization of alternate fuel when conditions permit its utilization, RIN extraction when renewable alternate fuel is utilized may be forfeited, as governmental entities may specify that RIN extraction to occur at time of blending with a fossil primary fuel. In another case however, RIN extraction may have already occurred with governmental entities thus mandating that the alternate fuel be utilized as a motor fuel in its neat form only. Additionally, state, county and municipal governmental entities may further provide local alternate fuel subsidies, credits or various mode restrictions based upon geographical boundary. With present art, differentiating these conflicting modes of operation to maintain legal compliance is problematic.
Yet another limitation may arise when primary fuel and alternate fuel are stored in separate fuel storage vessels, as typically the engine fuel pumping system and other engine components such as fuel injectors create bypassed fuel during their normal operation, said bypassed fuel being excess fuel not consumed by immediate engine combustion demand that must be returned to the fuel storage vessel also serving as the scavenge point and necessarily existing at a lower pressure than the output of the fuel pumping system or components producing said bypass. In this embodiment, some primary or secondary fuel will be entrained within the bypass system immediately following a change in fuel selection, thus cross-contaminating the primary and secondary fuel storage vessels. Likewise, RIN extraction when renewable alternate fuel is utilized may be forfeited, as governmental entities may choose to specify or interpret RIN extraction to occur at the time that the blending of the pure or neat renewable fuel with the fossil fuel occurs as the motor fuel is created, and any bypassing of primary fuel to the renewable fuel storage vessel would render it contaminated and no longer pure or neat, and therefore unsuitable for such purpose.
Therefore, an improved system and method of supplying an internal combustion engine with a primary fuel, an alternate fuel, or a combination of both is desired as to facilitate the maximum utilization of alternate fuels while simultaneously maintaining compliance with present and/or future governmental regulations and/or restrictions on use, and credit for renewable fuel utilization including the generation and tracking of renewable energy RIN-style trading methodologies as allowed.